Browse Prior Art Database

Signal Generator having Voltage Tracking Circuitry

IP.com Disclosure Number: IPCOM000116602D
Original Publication Date: 1995-Oct-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Miyazaki, Y: AUTHOR

Abstract

Disclosed is a signal generator which has a voltage tracking circuitry.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 82% of the total text.

Signal Generator having Voltage Tracking Circuitry

      Disclosed is a signal generator which has a voltage tracking
circuitry.

      The signal generator controls a Liquid Crystal Display (LCD)
panel at a visual inspection process.  The signal generator applies
control signals such as timing, image and reference voltages for LCD
drivers.  The voltage tracking circuit monitors LCD primary power
voltage and protects the LCD drivers from over voltage damages.

      The Figure shows the signal generator, the LCD panel and the
power supply.  The power supply applies primary power (Vp1) to the
LCD panel.  The LCD panel regulates Vp1 to LCD driver's source (Vdc).
The signal generator monitors Vp1 line (1).  The voltage tracking
circuit (2) applies an output buffer(4)'s source (Vbc).  (2),voltage
tracking circuit regulates Vp1 to Vbc, using a gain value table (3).
(4),output buffer drives control signals (Vso) characterized by a
impedance of a transmission line and the LCD panel driver input.

      To protect the LCD panel driver from over voltage damages,
signal level (Vso) should be kept lower than driver's source level
(Vdc).  Vdc is settled by a gain of the LCD panel regulator(Gr) and
the primary voltage (Vp1), Vdc=Gr*Vp1.  Vso is reduced from output
buffer source level (Vbc) by output impedance, Gb=Vso/Vbc.
Vso(=Gb*Vbc)<Vdc(=Gr*Vp1), Vbc<(Gr/Gb)*Vp1.

      If (2), voltage tracking circuit has a Gr/Gb gain, Vso is lower
than Vdc.  (3), gain ta...